Insect-inspired thoracic mechanism with non-linear stiffness for flapping-wing micro air vehicles

This paper presents the design, analysis and characterization of a compliant mechanism that saves power for flapping-wing micro-air vehicles (FWMAV). The compliant mechanism is shaped after the insect's flight thorax, which has integrated elastic hinges for energy storage. It shows a nonlinearly increasing stiffness, which slows the wings down rapidly toward the end of a wing stroke and reverses the wings quickly, just like the elastic radial stop in Dipteran insects. When used to drive a 10-cm wing span FWMAV, it saves power up to 31% in comparison to a conventional rigid-body flapping mechanism, which have no elastic storage capability.